mw13 and others: you are mistaken. Check “Igeres Teiman” from the Rambam. Clearly, Islam is not considered “avoda zarah’ for anyone. Islam recognizes one G-d for all, hence it is not avodah zarah. Mohammed is their prophet and has nothing to do with the deity they believe in.
X-anity is different as it has some aspects of “shituf’,which is certainly “avodah zarah” for Jews but not necessarily for others.